BBS centers are painted gold - My guess is that GT40's are also painted gold - I'd suggest buying some OEM Paint (German) that goes with Porsche, BMW, Mercedes - I'd also guess that the process involves the right paint and several applications of clear coat.
I had BBS wheels with gold centers on a Porsche Turbo - simply stunning and would be awesome on a black car.
From one site....
"The German design nozzle produces a fine, even spray that is easy to control and produces a near-factory finish. Wurth German Alloy Wheel Paint dries quickly and is chip resistant. Use several very light coats and allow 30 minutes drying time between coats. The gold and silver color coat will have a textured look and feel that provides a three dimensional effect when properly finished with a clear topcoat (use two coats of Wurth High Gloss Clear Lacquer as the final topcoat)."
http://www.hrpworld.com/index.cfm?fo...action=product
They've noted gold as not yet available.....